This application seeks to acquire a confocal enhanced episcopic fluorescence image capture (EFIC) system. EFIC imaging entails the capture of tissue fluorescence at the cut surface of paraffin embedded specimen. As each section is cut using a microtome with a fixed photo position, an epifluorescence image of the specimen exposed at the block face is captured. Given the photo position is invariant, the 2D image stack collected is in perfect registration, and thus can be digitally resectioned in any imaging plane. It also can be rapidly reconstructed to generate high-resolution 3D renderings of the specimen. In the first generation EFIC imaging system, surface fluorescence is captured with epifluorescence imaging using standard mercury illumination. To prevent bleed through fluorescence from beneath the block surface, aniline, a light blocking dye is incorporated into the paraffin wax via a laborious and difficult high temperature embedding process. With this proposal, we will assemble a 2nd generation EFIC imaging system that will obviate the need for high temperature paraffin embedding with aniline. Imaging will be carried out with the Leica widefield superzoom LSI confocal macroscope. As confocal imaging will allow capture of only surface fluorescence, it will eliminate the need for the incorporation of aniline dye in the paraffn. This makes it possible for any paraffin embedded specimen to be processed for EFIC imaging. In addition, with appropriate lasers and excitation/emission filters, EFIC imaging can be combined with the tracking of specific cell lineages using fluorescent protein tagged expression constructs. Overall, EFIC imaging achieves better resolution than images obtained by MRI, and has the advantage that it can be learned easily by most investigators, given it is essentially a histological technique combined with confocal imaging. The ability to digitally resection the 2D image stacks in any imaging plane and the ease for rapid 3D reconstructions are invaluable for the assessment and diagnosis of anatomical malformations such as that associated with congenital heart disease, or defects in vascular patterning or branching morphogenesis. In addition, quantitative assessment of anatomical structures can be carried out using the perfectly registered 2D image stacks or 3D reconstructions, such as vessel/tubule dimensions or their branching complexities, or the size of chamber lumen dimensions or tissue thicknesses. This confocal enhanced EFIC system will be assembled using off the shelf equipment, the Leica SM2500 microtome and the Leica LSI confocal macroscope. Customization required to affix and align the confocal macroscope to the photo position of the microtome has already been developed with generous seed funding from the School of Medicine and with the borrowed use of an LSI confocal mascroscope from the Department of Developmental Biology. Therefore, funding requested in this proposal will allow the immediate installation of a dedicated confocal EFIC imaging system. This will greatly enhance the research programs of six well funded NIH investigators, filling a gap in 2D/3D imaging technology for high resolution tissue structure analysis. PUBLIC HEALTH RELEVANCE: This application seeks to acquire a whole tissue imaging system that will provide detailed visualization of anatomical structures in three dimensions. This will facilitate the detection of alterations in tissues architecture associated with birth defects nd other acquired diseases, and allows quantitative analysis of anatomical and tissue defects to yield novel insights into disease mechanisms.